The present invention concerns a device to transmit power from the power system of a working machine to one or more moving parts of a tool replaceably attachable on a first part of the working machine which is in the form of a beam or such.
The working machine can be of any type and trucks, front loaders, digging machines and demolition machines can be mentioned as examples, which are generally supplied with different types of tools. The term “tool” also includes so-called working instruments, and examples of what is here intended to be thought of as tools are forks of different types, scoops, man-baskets, lever arms and other special equipment for handling special loads.
In order to illustrate the invention but without limiting the invention, the case of a tool in the form of a fork unit can be briefly described. Such a fork unit is used for the handling of pallets and other such goods. The fork unit is usually expected to have different functions which require some kind of driving, i.e. the unit has to be supplied with power (energy). Examples of such functions are that the forks could be driven apart or moved together depending on what kind of load is to be handled or that they could be laterally moved relative to a frame of the fork unit. The power required to carry out these functions is obtained by the fork unit from the working machine's power system according to known devices of the type defined in the introduction, usually a hydraulic system, since this device has components to rapidly interconnect the working machine's hydraulic system with a hydraulic cylinder arranged on the tool to carry out said functions.
This means that when a change of the tool on the working machine is desired the driver has to get out of the driver's cabin and manually interconnect said components for interconnection of the truck's hydraulic system with one or more hydraulic cylinders on the tool. This can be troublesome for the driver, and he can therefore sometimes be tempted to neglect to change the tool if this is not absolutely necessary and instead use an unsuitable tool. This can in its turn result in the risk of injury.
Another disadvantage with such known devices and this way of interconnecting the working machines hydraulic system with hydraulic cylinders on the tool lies in the fact that there are no such connection components that are completely protected against impurities in the hydraulic oil. This constitutes a decreasing operation safety factor as the use of proportional valves in hydraulic systems increases.